﻿#Region "Microsoft.VisualBasic::693eb2a3a9132d4165de7d98fd907131, XDRStream\EnumHelper.vb"

' Author:
' 
'       asuka (amethyst.asuka@gcmodeller.org)
'       xie (genetics@smrucc.org)
'       xieguigang (xie.guigang@live.com)
' 
' Copyright (c) 2018 GPL3 Licensed
' 
' 
' GNU GENERAL PUBLIC LICENSE (GPL3)
' 
' 
' This program is free software: you can redistribute it and/or modify
' it under the terms of the GNU General Public License as published by
' the Free Software Foundation, either version 3 of the License, or
' (at your option) any later version.
' 
' This program is distributed in the hope that it will be useful,
' but WITHOUT ANY WARRANTY; without even the implied warranty of
' MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
' GNU General Public License for more details.
' 
' You should have received a copy of the GNU General Public License
' along with this program. If not, see <http://www.gnu.org/licenses/>.



' /********************************************************************************/

' Summaries:

'     Class EnumHelper
' 
'         Constructor: (+1 Overloads) Sub New
'         Function: EnumToInt, IntToEnum
' 
' 
' /********************************************************************************/

#End Region

Public Class EnumHelper(Of T As Structure)

    Private Shared ReadOnly _enumMap As Dictionary(Of T, Integer)
    Private Shared ReadOnly _intMap As Dictionary(Of Integer, T)

    Shared Sub New()
        Dim underType As Type = GetType(T).GetEnumUnderlyingType()
        Dim conv As Func(Of T, Integer)

        If underType Is GetType(Byte) Then
            conv = Function(item) CByte(CType(item, ValueType))
        ElseIf underType Is GetType(SByte) Then
            conv = Function(item) CSByte(CType(item, ValueType))
        ElseIf underType Is GetType(Short) Then
            conv = Function(item) CShort(CType(item, ValueType))
        ElseIf underType Is GetType(UShort) Then
            conv = Function(item) CUShort(CType(item, ValueType))
        ElseIf underType Is GetType(Integer) Then
            conv = Function(item) CType(item, ValueType)
        Else
            Throw New NotSupportedException(String.Format("unsupported type {0}", GetType(T).FullName))
        End If

        _intMap = New Dictionary(Of Integer, T)()
        _enumMap = New Dictionary(Of T, Integer)()

        For Each item In [Enum].GetValues(GetType(T)).Cast(Of T)()
            Dim exist As T = Nothing
            Dim key = conv(item)
            If Not _intMap.TryGetValue(key, exist) Then _intMap.Add(key, item)
            If Not _enumMap.TryGetValue(item, key) Then _enumMap.Add(item, conv(item))
        Next
    End Sub

    Public Shared Function IntToEnum(val As Integer) As T
        Dim exist As T = Nothing
        If _intMap.TryGetValue(val, exist) Then Return exist
        Throw New InvalidCastException(String.Format("type `{0}' not contain {1}", GetType(T).FullName, val))
    End Function

    Public Shared Function EnumToInt(item As T) As Integer
        Dim val As Integer
        If _enumMap.TryGetValue(item, val) Then Return val
        Throw New InvalidCastException(String.Format("enum {0} not contain value {1}", GetType(T).FullName, item))
    End Function
End Class
